Carrying a power bank for your phone is second nature these days—but what about your laptop? If you’ve ever tried to plug your computer into a portable charger and got nothing, you’re not alone. Not every power bank has the wattage to handle laptop-level power demands.
So how many watts do you actually need to charge a laptop efficiently—and what should you look for before buying one? Let’s break it down.
Why Laptop Charging Requires More Power
Smartphones and tablets usually need 10–30 W to charge. Laptops, on the other hand, are in a different league. Their processors, graphics chips, and larger batteries all draw significantly more power.
Here’s the key difference:
- Phones: 5–20 W charging (USB-C or Lightning)
- Tablets: 15–30 W
- Laptops: 45–100 W (and sometimes more)
That’s why plugging your laptop into a 10 W or 20 W phone charger does almost nothing—it simply doesn’t have enough wattage to make a difference.
To understand how many watts your laptop needs, you first have to know how its power system works.
What “Watts” Actually Mean
Wattage (W) measures how quickly energy flows from your power bank into your device. It’s calculated as:
Watts = Volts × Amps.
For example, a laptop that charges at 20 V × 3 A = 60 W requires a power bank capable of supplying at least 60 W output through its USB-C or DC port.
If the power bank’s maximum output is lower—say, 30 W—it may not charge your laptop at all, or it will charge extremely slowly (and might even lose power while in use).
The Role of USB-C Power Delivery (PD)
Most modern laptops—and the power banks designed to charge them—use USB-C Power Delivery (PD), a universal standard that negotiates how much power a device can handle.
Here’s how it works:
- When you plug in, the power bank and your laptop “communicate.”
- The laptop requests a certain voltage (typically 5 V, 9 V, 15 V, or 20 V).
- The power bank automatically adjusts its output to deliver the correct wattage.
Because of this smart handshake, your laptop only draws what it needs. But the power bank still must offer enough headroom to meet that demand.
Common Laptop Wattage Requirements
Different laptops have different power ratings, depending on brand, size, and purpose. Here’s a general guide to what various models need:
| Laptop Type | Typical Charging Wattage | Notes |
| Ultrabooks / Thin-and-Light (13″) | 30 W – 45 W | Ideal for basic office use and web browsing |
| Mainstream Laptops (14–15″) | 45 W – 65 W | Standard work or student laptops |
| Performance Laptops / Gaming Models | 90 W – 130 W+ | High GPU and CPU power draw |
| MacBook Air (M1 / M2) | 30 W – 35 W | Efficient Apple silicon chips |
| MacBook Pro 13″ / 14″ | 60 W – 96 W | Needs a 60 W+ power bank for optimal results |
| Windows Business Laptops | 45 W – 65 W | Dell XPS, HP EliteBook, Lenovo ThinkPad, etc. |
| Chromebooks | 30 W – 45 W | Low to medium demand |
If your laptop uses a dedicated AC adapter rated at 65 W, then you’ll need a power bank capable of delivering at least 65 W of USB-C PD output. Ideally, choose one slightly higher—around 70 W or more—to avoid performance drops.
Why a Lower-Watt Power Bank Might Fail
Even if you plug in a cable that fits, a low-watt power bank won’t always work.
Here’s what can happen:
- No charging at all: The laptop detects insufficient power and refuses to charge.
- Slow charging: The power bank struggles to keep up, especially while you’re using the laptop.
- Battery drain while plugged in: The laptop consumes more power than it’s receiving.
This is common with larger laptops (like 15″ or 16″ models) connected to 30 W or 45 W chargers. It’s not unsafe, but it’s inefficient—you’ll end up with a warm charger and a battery that never hits 100%.
The Sweet Spot: 60 W to 100 W Power Banks
If you want reliable laptop charging, look for power banks rated between 60 W and 100 W.
- 60 W: Works for smaller or energy-efficient laptops (e.g., MacBook Air, Chromebook, Dell XPS 13).
- 65 W–87 W: Covers most standard work laptops.
- 100 W: Handles nearly all USB-C laptops, including high-end MacBook Pro and gaming ultrabooks.
A few top-tier models now support dual-port 100 W output (for laptops) plus additional 20 W ports (for phones and tablets). This lets you power multiple devices simultaneously without slowing down your main laptop charge.
How to Check Your Laptop’s Wattage
You can find your laptop’s power requirements in several ways:
- Look at your original charger. The label usually reads something like “Output: 20 V ⎓ 3.25 A = 65 W.”
- Check your device specs online. Search for “[your laptop model] + charging wattage.”
- Use your system settings. Some laptops (especially Windows 11 and macOS) show charging info when connected.
Once you know that number, pick a power bank with a higher or equal wattage rating. If your charger says 65 W, aim for at least a 65 W PD output—preferably 80–100 W for flexibility.
Charging Speed and Efficiency
Not all 65 W chargers perform the same. Environmental factors and internal conversion losses affect how efficiently energy moves between your power bank and laptop.
Here are some general guidelines:
| Power Bank Output | Laptop Charging Speed |
| 30 W | Slow or may not charge while in use |
| 45 W | Works for light laptops, slow for larger ones |
| 60 W | Standard charging rate for most laptops |
| 100 W | Full-speed charging even during heavy use |
For example, a 60 W charger can refill a 13″ ultrabook in roughly 2 hours, while a 100 W charger can fully power a MacBook Pro 16″ under heavy load.
Don’t Forget the Cable
Even the most powerful power bank is useless without the right cable. To handle high wattage safely, you need a USB-C cable rated for 100 W (5 A).
Lower-rated cables (3 A max) can bottleneck performance or overheat during charging. Look for markings like “E-Marked 100 W” or “PD 5A Certified.”
Always match the cable’s wattage with your power bank’s maximum output for best results.
How Long Can a Power Bank Run a Laptop?
Let’s say you have a 20,000 mAh (≈ 74 Wh) power bank rated for 65 W. How much runtime does that give your laptop?
Example:
A typical ultrabook consumes about 20 W–30 W under light use.
74 Wh ÷ 25 W ≈ 3 hours of extra runtime.
For larger laptops drawing 50 W–60 W, expect around 1.5 hours.
Keep in mind that efficiency losses (10–15%) are normal, especially if you’re multitasking or gaming.
Can You Charge and Use the Laptop at the Same Time?
Yes—but wattage is everything.
If your power bank provides equal or greater output than your laptop’s demand, it can charge and power it simultaneously. But if the output is lower, the laptop will use battery power to compensate, meaning you’ll slowly drain even while plugged in.
So if you plan to work for hours on the road, choose a high-output model (80–100 W) to maintain steady performance.
Air Travel and Watt Limits
When flying, airline rules restrict lithium batteries based on watt-hours (Wh), not watts of output. Most carriers allow up to 100 Wh per power bank, and some allow up to 160 Wh with prior approval.
Since most 20,000 mAh laptop power banks fall around 70–80 Wh, they’re usually safe to bring on board. Just remember:
- Carry in hand luggage (not checked).
- Keep terminals covered or disconnected during flight.
This makes high-output power banks a practical companion for business travelers who rely on laptops mid-flight.
Future Trends: More Power, Less Weight
Technology is evolving fast. Newer gallium-nitride (GaN) components make power banks smaller, lighter, and more efficient—even at 100 W or higher.
Some upcoming models promise dual 100 W outputs, meaning two laptops could charge at once. Others support bi-directional charging, allowing the same USB-C port to both charge the power bank and output power to a device.
As power density improves, expect 25,000 mAh (≈ 93 Wh) units to become the new standard for professionals and travelers.
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Quick Buying Checklist
When choosing a power bank for your laptop, check these essentials:
✅ Wattage: At least equal to your laptop’s original charger (typically 45–100 W).
✅ USB-C Power Delivery (PD 3.0 or higher): Ensures safe and efficient charging.
✅ Capacity: 20,000 mAh + for useful runtime.
✅ Cable compatibility: Use certified 100 W USB-C cables.
✅ Pass-through charging (optional): Lets you charge the power bank and laptop simultaneously.
✅ Airline compliance: Under 100 Wh for carry-on travel.
Conclusion
The wattage of your power bank determines whether it can truly charge your laptop or just keep it on life support. For most modern notebooks, aim for 60 W – 100 W USB-C PD output to ensure smooth, reliable performance.
A well-matched high-wattage power bank doesn’t just extend your laptop’s battery life—it gives you true mobility and independence from wall outlets, wherever work (or adventure) takes you.
